The specific objectives for the current period of investigation are: I. Cloning of the BamHI R/M enzymes a. Polynucleotide synthesis and purification. b. Solution of DNA probes for cloning of BamHI restriction modification enzyme genes. c. Options for cloning of R/M genes. d. Determination of primary sequence of BamHI R/M enzymes as inferred from DNA sequences. II. Physical and biochemical studies on BamHI R/M enzymes. a. Crystallization of BamHI endonuclease b. Co-crystallization of BamHI and the cognate oligonucleotides c. Preparation of BamHI palindrome with modified flanking sequences d. Analysis of BamHI Kinetic Data e. Reaction rates of BamHI endonuclease with variations in the location of the recognition sequence. III. Studies on HinGUII R/M enzymes a. Purification of restriction modification enzymes. b. Characterization of modification enzymes(s). c. Identification of the modification acceptor.